public class demo1 {
    public static void main(String[] args) {
//        String s1="A"+"C";
//        String s2 = s1+"B";

        String s1="hello";
        StringBuilder stringBuilder=new StringBuilder(s1);
        StringBuilder reverse = stringBuilder.reverse();
    }
}


abstract class A{
    private String a;
    public void get(){

    }

    static void get2(){

    }
}